This invention relates generally to coupling devices for controlling plate sequences in a mold where multiple parting lines are required, and more particularly to plate locks or latch locks for multi-plate molds.
Tripartite injection or compression molds, especially for forming of plastic pieces, incorporate a two-stage separation of plate components to facilitate the ejection of one or more pieces formed in a mold-closed position. Coupling devices are used to hold a second separation stage in a closed position until the first separation stage has reached a certain gap width. Upon reaching the desired gap width, the coupling device releases the second separation phase.
Currently, different mechanisms are used for such a coupling device. Common coupling devices include a locking bar fixed to one plate and secured to a movable element on a second plate. When the movable element is moved, the locking bar is released and the plates separate. Often coupling devices break during use because of the force put on the thin steel. It is not uncommon for end-users to modify parts of the coupling devices by adding extra material for strength even before the devices are installed within the molds. There is a continuing need for an improved coupling device.